The Pew Research Center study on “The World’s Muslims” has generated a great deal of domestic and international attention. We have received many emails from readers and are grateful for the interest and feedback. Here are answers to some of the most common questions we have been receiving. Readers who have other questions are invited to send them to us; when possible, responses will be posted in the future.

How did you select the countries for the Pew Research Center’s survey of Muslims around the world?

We set out to survey in all countries where Muslims constitute either a majority of the population or a very large minority (10 million or more). We succeeded in most cases. As we noted in the preface to the report, however, in a few countries we were unable to conduct face-to-face interviews, primarily due to cultural and political sensitivities associated with the topics of religious identity and belief. In such environments, the quality of data may be undermined if respondents do not feel free to express their true opinions. In addition, the safety of interviewers may be at risk if the survey meets objections from local residents or authorities. Based on a careful assessment of the conditions under which face-to-face surveys could be conducted, we judged that we could not meet our high standards for the safety of interviewers and data quality in some countries. We hope that circumstances will change and that in the future we will be able to conduct surveys on religion in all the places excluded from the current study.

How can you call a survey that excludes Saudi Arabia, India and China a “global” survey of Muslims?

Although we decided that we could not safely and reliably conduct face-to-face interviews on religion in a few countries, including Saudi Arabia, India and China, we were able to survey in a total of 39 countries that collectively are home to approximately 67% of the world’s 1.6 billion Muslims. These countries span the globe from Africa and the Middle East to Europe and Asia. Across these regions, the survey captures the views of Muslims in a wide range of social, cultural and political contexts. The results of the survey – from divergent views about sharia to differences over women’s rights to varying attitudes toward violence in the name of Islam – provide empirical evidence that the survey represents a broad, as well as in-depth, picture of how Muslims see themselves and their societies in the modern world.

Why weren’t Muslims in Western European countries included in this survey?

Pew Research previously has conducted public opinion polls among largely immigrant religious groups in both the United States and Europe. We surveyed Muslim Americans in 2007 and 2011, as well as Muslims in Britain, France, Germany and Spain in 2006. We believe that studies of immigrant communities should give special attention to issues related to integration, assimilation, discrimination and identity. These issues were beyond the scope of the current project, which focused on countries that have Muslim majorities or populations of at least 10 million Muslims.

The current report does offer some comparisons between U.S. Muslims and Muslims in other countries in Appendix A. It is our hope that in the future we will be able field surveys of European Muslims and provide similar cross-national comparisons.

Why didn’t you ask questions about sharia in the U.S.?

The goal of the 2007 and the 2011 studies of Muslim Americans was to understand how respondents view being a Muslim in the United States, especially after the events of Sept. 11, 2001. To this end, we included many questions about attitudes toward social and political issues in the U.S., experiences with discrimination and views on religious extremism.

“The World’s Muslims” study, by comparison, has a much stronger focus on religious beliefs and practices and related attitudes, including how Muslims interpret sharia and how they apply sharia in their daily lives.

Because the goals of the Muslim Americans surveys and the current study were different, there was only limited overlap between the two studies. “The World’s Muslims” report describes the results of the overlapping questions in Appendix A.

Why weren’t all the same questions asked in every country included in “The World’s Muslims”?

Conducting opinion polls in diverse societies requires adapting the questionnaire to local sensitivities and conditions. The survey was pre-tested in each country in order to assess whether respondents would understand and be comfortable answering the questions. In some countries, the pre-test results indicated that to avoid offending respondents or placing interviewers at risk, it was best to modify or remove certain questions. Thus, not all survey questions were asked, or identically phrased, in all countries.

For example, as a result of pre-tests, interviewers in Afghanistan, Uzbekistan and Morocco indicated that certain questions related to sexual conduct were too sensitive to be asked. Questions on this topic were either eliminated or modified in these countries.